Conditioning treatment for cooling systems after acid cleaning



United States Patent. C)

CONDITIONING 'mizA NT F0111 COOLING SYSTEMS AFTER ACID CLEANING CharlesF. Pickett, Bel Air, and Myer Rosenfeld, Balti- Patented June 27, 1961two phases must be performedseparately. Inco rating thesilicatetreatment with the alkalinecleaning step offers no advantage over nosilicate at all. The one must necessarily follow the other to obtainthedesired result Theremore, 'Md., assignors' to the United States ofAmerica 5 g the smcatisuluiion i drained from i as represented by theSecretary of the Amy I f e ore the a-lkalme i 15 muoducgd' No DrawingFiled Jam 7, 1960, s 1,140 7 After a water cooling system has-been acidcleaned, 9 Cl i (C 134-22 with perhaps, the acid cleaners of the typedisclosed n (Granted under Tifle 35, U.S. Code (1952), see. 266) Pa nt2, 3 50 n e sy m h r ghlyfiushed 10 with water the process of thisinvention is then applied. The invention described herein may bemanufactured Suflicient alkali metal silicate solution is added to theby or used for the Government for governmental purposes system to obtaina concentration of silicate of from about without the payment to us ofany royalty thereon. 0.5 to 4.0 percent by volume. The system is thenbrought This invention relates to a process and composition to atemperature of from about 160 -480 F. for apfor prolonging the use lifeof internal combustion engine proximately fifteen minutes and is, thendrained. lf de cooling systems and more particularly concerns aprocsired, this latter period may extend anywhere fromfive ess andcomposition for conditioning such cooling sysminutes to four hours. Thesystem is refilledwith fresh tems subsequent to treatment with acidcleaning composiwater, leaving some space for the alkaline rinse solidstions.' p i that are to be added or, if preferred, the alkaline solidsVarious acid, cooling systemcleaners are known to may beadded in thefresh water. The alkaline solids the art. Of particular interest in thisrespect isthe highly comprise a mixture of an alkali metal phosphate orpolyeffective acid cleaner disclosed in U.S. PatentNo. 2,631,- phosphateand an alkali metal tetraborate. The prefer- 950. Normally, aftertreatment with such acid cleaners, red alkaline metal phosphate istrisodium phosphate and an ordinary flushing operation is employedto'comp'ljejtely the preferredalkaline metal tetraborate is sodiumtetraremove the acid and loosenedsoil. Previously, it was borate. Thealkali phosphateis present within a concenthought that such ordinaryflushing was sufiicient to actration of from about 0.5 to 4.0 percent byweight. The complish this purpose. Howeven'it' has been found thatalkali tetraborate' is present;within a concentration of after a fewmonths use of cooling systems, that have been 0 from about 0.5 to 3.0percent by weight. Sodium carbonacid cleaned and flushed in the usualmanner there is a ate may optionally be included in the alkaline rinsesolunoticeable increase in the chloride content of the coolant. tion inconcentrations up t'o about 1.0 percent by weight. For example, acoolant having an initial chloride content This system is brought to atemperature 'of from about of 6 parts per million in a month was foundto have a 160180 F. for approximately 'five minutes to four chloridecontent of 200 parts per million. This build up hours. of chloridecontentis due to the presence of soil which i It has been discoveredthat the important consideration was loosened during the acid cleaningprocess but. was in conditioning the cooling systems isnot so much tonot removed by conventional flushing processes. This obtain superiorinhibitory action, as it 'is-to strike a balloosened soil graduallyenters the coolant, carrying with ance between deactivation of thesurface and thoroughit entrapped chlorides. Although'ithas long beenrecv ness of elimination of residueloosenedby the acid cleanognized thatavery thorough flushing is needed subsequenting treatment but notremoved by the subsequent water to the acid cleaning of cooling systems,it Wa not P 40 flush. This balance concerning deactivation of thesurviously realized that such flushing is ineffectual in r'emQV- faceand elimination of residue is attained following the ing soils whichhave been loosened butnot actually retwo-step process disclosed herein.The experimental evi-- moved from the surfaces of the cooling system:which has dence shows that the multiple components of the, second; beenacid cleaned. p v step, the alkali metal phosphate and tetraborate, actto? g y, a Objective of this invention is to pro ide. gethersynergistically to provide for better surface deacti means forconditioning acid cleaned cooling, systems. vationjthan is obtained whenthe components are'used A further object of the invention is to providea method individually. By X-ray diffraction analysislof the adhereforthe removal of residues loosenedv by acid cleaners. ing deposits in thecooling system it was determined that .1 but not removed without the useof a flushing machine; 1 there was a fundamental difference betweenthesili'c'a'ted A further object of the invention is to provide aprotreated systems and those not so treated. The two-"step cess andcomposition that is capable of deactivating the conditioning treatmentis known to produce a very effecsurfaces of internal combustion enginecooling systems. tive coating on they metal surface. that deactivatessaid.

Briefly, the conditioning treatment of this invention in-j surface. Thisnew conditioning process can extend the volves two separate phases orsteps. The first phase con use life of the cooling system over fourtimes that realized sists of circulating through the system analkalimetal with the current conditioning methods. I silicate solution.The second phase consists-of circulatk The following are. workingexamples given forthe puring through the system an alkaline rinsesolution.- -"I'he pose of specifically illustrating how the process maybe alkaline solution comprises a mixtureof an alkali metal performed. pj. s phosphate and an alkali metal borate. The alkaline rinse Variousillustrations of concentration coming within" solution may optionallycontain sodium carbonate. The 9 the scope of the invention are thefollowing:

(allbysgglllg'llflsfllcate Salmon 40 Baum' percent 0.5 0.5 0.5 0.5 1.22.0 2.0 2.0 2.0 4.0 4.0 4.0 (b) Alkaline Cleaning Mix:

Trisodium phosphate, weight percent of Na,1 0..1211,o 0.5 4.0 4.0 0.51.8 0.0 4.0 2.0 0.5 2.0 0.5 4.0 Milli-moi percent, any hydrate, alkalinepolyphosphate, alkaline phosphate 1.3 10.5 10.5 1.3 4.7 1.3 10.5 5.3 1.35.3 1.3 10.5 Sodium tetraborate, weight percent 01' 1031340 101110 0.53.0 0.5 0.5 1.2 0.5 3.0 1.5 0.5 1.5 0.5 3.0 i 0 c moigiii iil-ifiiifiilnfii i- 1.3 7.0 1.3 1.3 3.2 1.3 7.9 1.3 1.3 3.9 1.3 3.9 Sodiumcarbonate, weightpercent of Nezgoh. 0.0. 1.0 0.0 1.0 0.3 0.0 1.0 0.3 0.30.3 0.0 1.0 Mzlwildilfolpement'Naloomfiaomthzww 0.0 0.4 0.0 9.4 2.8 0.00.4 2.8 2.8 2.8 0.0 9.4

Milli-moi percents in the .above indicate the concentra-. tions neededregardless of degree ot' hydration.,;1he soaiumsnica e solutionreferred' tohaS 'a ratio of sodium oiide tosilica of notore than'lz2'notless than 153.5. The respective solutions noted in the abovetable, '(a) and-(b), are separately circulated throug h the coolingsystem that is to be conditioned. The-timeof treatment varies widelyfrom fiveminutes to four hours, and depends upon the concentration ofthe solution; weaker solutions require-more time. The preferred."embodiment is Example -5 above and the alkaline mix is circulated forabout one hour; g

The superiority of this new conditioning treatment; lies in thefact thatsimultaneously with deactivation, corrosive products are suflicientlyeliminated so as not to clog the cooling system on subsequent use. Thechloride content is known to be indicativego f the amount of soilpresent in the system; Fresh water has a chloride content-of about '6parts per million. Cooling systems treated with the conventional acidcleaners andflushed'nntil the The alkali tetraborate plus the alkaliphosphate form a synergistic detergent, as borate alone gives noimprovement in chloride build up. in yehicle studies when used foronehour at 1 60 -180' F. 'a'sthe alkaline rinse. Then too, "theflaveragechloride "content climbs to, 84 p.plm. after ZOQ'hoursOperation -in the.dynamometer when a trisodium phosphate rinse .isused. alone, but to 32p.p.m. when the tetraborate-phosph ate mix is used for the alkalinerinsebfthecondititanirig step.- Thus, the increased detergency of thecombination is-re'adily apparent. Such increase would not be predictablefrom the data, as the borate alone gives no detergency effect whatsoeverunder these conditions and the gency effect. 7

In the foregoing description we have disclosed preferred embodiments ofthe invention. However, it is not intendphosphate gives a weak deter Ied that't-his invention be limited by specific examples set waterdrainings have-a chlorideflcontent, of '6 parts per 7 million have aftera month of use a chloride content of 200 parts-per million. Studieswith'the presentinvention disclose the following results: Y

' Chloride contents :in parts per million after at least 200hours indynamometer The maximumchloride level 'obtainedr with trisodiumphosphate plus sodium tetraborate after 400v hours was 37 p.p.m.Addition of two ounces of sodium carbonate to the alkaline cleaning mixwas made, primarily from .a corrosion inhibition viewpoint. In thecomparison study this further'reduc'ed the average to about 17 p.p.m. in400mm- Corresponding dynamome'ter studies without an alkaline rinseclimbed to at least 84' p.pLmJin 400 hours. For the unusedv cleaneddynamometer cooling system (new) 12 p.p.m. was found. Hence, .an averageof 1 7- l2=$ p.p.m. can be associated with residual soil unremoved bythe alkaline cleaning treatment. Since 84-'12=72 p.p.m., this isassociated with residual soil without alkalinecleaning rinse, 6 or 7percent remains unremoved, and the alkaline cleaning rinse is on theaverage 93 percent successful .on this chloride criterion. Thissignificant reduction in the .chloridecontent in parts per million meansthe life of the cooling system after acid cleaning can be increasedsome400 percent.

" tetraborate.

forth above and it will be apparent to those skilled in the artthatvariations maybe made without departing from the spirit of the inventionas defined in the claims;

We claim: LA process of conditioninga cooling system after acid cleaningcomprising the steps of circulating through the system an alkali metalsilicate solution, draining said solution and rinsing said system withan alkaline solution containing an. alkali metal phosphate and-analkalimetal 2; The process accordin'g to claim 1 in which saidalkaperature range of the solutions during treatment is maintainedbetween about 160? 10180" F.

4. The process of conditioning a cooling system after acid cleaningcomprising the steps of circulating through the system an alkali metalsilicate solution, draining said v solution-and rinsing said system withan alkaline solution line rinse solution contains not comprising, 'byweight, of about 0.5 to 4.0 percent of an alkali metalphosphate andabout 0.5 to 3.0 percent of an alkali metal tetraborate.

5. The process according to claim 4 in which said alkamore than 1.0percent by weight of sodium carbonate.

' 6. The process according to claim 4 in which said silicate solution ispresent in amounts of about 0:5 to 4.0 percent by volume. V

7. The process according to claim 4 wherein .the temperature range ofthe solutions during treatmentis maintained between about to F.

8. The process of conditioning a cooling system after acid cleaningcomprising the steps of circulating through the system about 0.5 to 4.0percent by volume of a sodium silicate solution, draining said solution,and rinsing said system with an alkaline solution comprising, by weight,about 0.5 to 5.0 percent trisodium phosphate and about 0,510 3.0 percentsodium tetraborate.

9. The process according to claim 8 in which said "alkaline rinsesolution contains up to about 1.0 percent by weight sodium carbonate.

No references cited.

1. A PROCESS OF CONDITIONING A COOLING SYSTEM AFTER ACID CLEANINGCOMPRISING THE STEPS OF CIRCULATING THROUGH THE SYSTEM AN ALKALI METALSILICATE SOLUTION, DRAINING SAID SOLUTION AND RINSING SAID SYSTEM WITHAN ALKALINE SOLUTION CONTAINING AN ALKALI METAL PHOSPHATE AND AN ALKALIMETAL TETRABORATE.